Re: [?] Why should Distros be called as i386 for a 32-bit PC, and as amd64 for a 64-bit PC, when Intel Core PCs are also 64bit systems
On Sun, Mar 14, 2021 at 07:19:25AM -0400, The Wanderer wrote:
> On 2021-03-14 at 06:49, Susmita/Rajib wrote:
>
> > While Intel PCs are also 64bit processors?
>
> Because of the history of the processor microarchitectures involved.
>
> The x86 processor line (32-bit and older) was, to the best of my
> knowledge, originally an Intel thing. Before i386 (where the 'i' may
> stand for Intel, I'm not sure), there was 286, and other things earlier
> than that; if my memory just offhand is accurate, the oldest one was
> probably called 8086. After i386, you have 486, 586, and 686; current
> Debian 32-bit packages are actually compiled against the 686 baseline,
> not 386 as such.
>
> Intel owns the patents for the 32-bit x86 CPU architecture, and licenses
> them to other companies for a price. AMD is one of those other
> companies; that's how AMD is allowed to create 32-bit x86 CPUs.
>
> When 64-bit came along, rather than extending the x86 line, Intel
> started from scratch and designed an entire new CPU architecture. That
> got called ia64, and it never caught on; it eventually failed in the
> marketplace, except possibly in very limited market segments.
> when Intel created a 64-bit architecture (called ia64), it turned out to
> be a developmental dead end and failed in the marketplace.
>
> At around the same time, AMD created a 64-bit CPU architecture which
> extended the x86 line, and was backwards compatible with existing
> software. That got called amd64, and is also sometimes called x86_64, or
> other names in addition. It caught on, and became so successful that
> Intel abandoned its ia64 approach and started making amd64 CPUs itself.
>
> AMD owns the patents for the 64-bit amd64 CPU architecture, and licenses
> them to other companies for a price. Intel is one of those other
> companies; that's how Intel is allowed to create 64-bit amd64 CPUs.
>
>
> Or, put briefly: because AMD created the underlying design for how that
> type of CPU works, even if Intel is the one making the specific CPU
> model in question.
>
That is an excellent summary.
The only thing I would add is that Intel, an effort to not appear
completely buffoonish, does not refer to amd64. They might use x86_64
more commonly now (I'm not certain), but for a quite some time they used
the designation "em64t" (standing for something like "ehananced memory
64-bit something or other"). Occasional references to em64t can be
found in some places. It refers to the same thing: amd64 <-> x86_64 <->
em64t.
It was a bitter pill to swallow for Intel that they, as the originators
of the x86 architecture could have been so far off when it came to the
development of the successor 64-bit architecture.
Regards,
-Roberto
--
Roberto C. Sánchez
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